Chapter 6

1. What is a sampling distribution?

2. When the mean of the sampling distribution ( x ) would be

approximately normally distributed?

3. What is difference of the shape of the distribution of sample mean ( x )

and the shape of the distribution of x?

Hint: If there is a change of or , then it might affect the shape

Chapter 7

1. Explain the difference between the point estimate and interval

estimate (confidence interval).

2. What is margin of error?

3. Why must we use the point estimate p (sample proportion) in the

calculation of the standard error when producing a confidence

interval for p (population proportion)?

4. As sample size increases, what is the effect on the margin of error?

Why?

5. As confidence level increases, what is the effect on the margin of

error? Why?

6. What determines whether to use a t-distribution or a normal distribution

for finding a confidence interval for ?

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7. What is the condition to use Chi-squared distribution when estimating

the population standard deviation?

8. Describe the shape of a chi-squared distribution. How does the shape

change as the number of degrees of freedom increases? When degree of

freedom is larger than 30, what does the shape look like?

Chapter 8

1. What are null hypothesis and alternative hypothesis?

2. In a statistical test, we have the choice of a two-tailed test, a lefttailed test, or a right-tailed test. Which hypothesis is the

determining factor for choosing the direction of the test?

(In other words, how would you decide it)

3. For the same sample data and null hypothesis, how does the

P-value for a two-tailed test compare to that for a one-tailed test?

4. Using P-value method, how would you reject or fail to reject the null

hypothesis? (what is the decision criteria?)

How does level of significance matter to the hypothesis testing?

5. If the P-value is such that you can reject Ho at the 5% level of

significance, can you always reject Ho at the 1% level? Explain.

6. What do we mean when we say the data used in a statistical test are

significant?

7. In class we mentioned: "If you are conducting a study and want to

use a hypothesis test to support your claim, the claim must be worded

so that it becomes the alternative hypothesis".

Please Explain.

8. In hypothesis testing, why it is more appropriate to use "Fail to reject

to H0" instead of "Accept H0"?

9. What is test statistics? Calculating a test statistics will vary, please

list one example here.

10.Explain the type I and type II error.

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11. Describe the general steps to use traditional Critical Region

methods.

Chapter 10

1. Describe the relationship between two variables when the

correlation coefficient r is

a) near -1

b) near 0

c) near +1

2. What is the meaning of the "least-squares" criterion?

3. "Correlation does not imply causation." Explain.